Diverticula are small, bulging pouches that can form in the lining of your digestive system. They are found most often in the lower part of the large intestine (colon). Diverticula are common, especially after age 40, and seldom cause problems.

Sometimes, however, one or more of the pouches become inflamed or infected. That condition is known as diverticulitis (die-vur-tik-yoo-LIE-tis). Diverticulitis can cause severe abdominal pain, fever, nausea and a marked change in your bowel habits.

Mild diverticulitis can be treated with rest, changes in your diet and antibiotics. Severe or recurring diverticulitis may require surgery.

The signs and symptoms of diverticulitis include:

Pain, which may be constant and persist for several days. Pain is usually felt in the lower left side of the abdomen, but may occur on the right, especially in people of Asian descent.

Nausea and vomiting.

Fever.

Abdominal tenderness.

Constipation or, less commonly, diarrhea.

Diverticula usually develop when naturally weak places in your colon give way under pressure. This causes marble-sized pouches to protrude through the colon wall.

Diverticulitis occurs when diverticula tear, resulting in inflammation or infection or both.

Diet high in animal fat and low in fiber, although the role of low fiber alone isn't clear.

Certain medications. Several drugs are associated with an increased risk of diverticulitis, including steroids, opiates and nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil, Motrin IB, others) and naproxen (Aleve).

About 25 percent of people with acute diverticulitis develop complications, which may include:

An abscess, which occurs when pus collects in the pouch.

A blockage in your colon or small intestine caused by scarring.

An abnormal passageway (fistula) between sections of bowel or the bowel and bladder.

Peritonitis, which can occur if the infected or inflamed pouch ruptures, spilling intestinal contents into your abdominal cavity. Peritonitis is a medical emergency and requires immediate care.

You may be referred to a doctor who specializes in disorders of the digestive system (gastroenterologist).

What you can do

Be aware of any pre-appointment restrictions, such as not eating solid food on the day before your appointment.

Write down your symptoms, including any that may seem unrelated to the reason why you scheduled the appointment.

Make a list of all your medications, vitamins and supplements.

Write down your key medical information, including other conditions.

Write down key personal information, including any recent changes or stressors in your life.

Ask a relative or friend to accompany you, to help you remember what the doctor says.

Write down questions to ask your doctor.

Questions to ask your doctor

What's the most likely cause of my symptoms?

What kinds of tests do I need? Do these tests require any special preparation?

What treatments are available?

Will the diverticulitis come back?

Should I remove or add any foods to my diet?

I have other health conditions. How can I best manage these conditions together?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask other questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to go over points you want to spend more time on. You may be asked:

When did you first begin experiencing symptoms, and how severe are they?

Have your symptoms been continuous or occasional?

What, if anything, seems to improve or worsen your symptoms?

Have you had a fever?

What medications and pain relievers do you take?

Have you had any pain with urination, or passed air with urination?

Have you ever had a screening for colon cancer (colonoscopy)?

Diverticulitis is usually diagnosed during an acute attack. Because abdominal pain can indicate a number of problems, your doctor will need to rule out other causes for your symptoms.

Your doctor will likely start with a physical examination, including checking your abdomen for tenderness. Women, in addition, generally have a pelvic examination to rule out pelvic disease.

After that, your doctor will likely recommend:

Blood and urine tests, to check for signs of infection.

Pregnancy test for women of childbearing age, to rule out pregnancy as a cause of abdominal pain.

Liver function tests, to rule out other causes of abdominal pain.

Stool test, to rule out infection in people who have diarrhea.

CT scan, which can indicate inflamed or infected pouches and confirm a diagnosis of diverticulitis. CT can also indicate the severity of diverticulitis and guide treatment.

Treatment depends on the severity of your signs and symptoms.

Uncomplicated diverticulitis

If your symptoms are mild, you may be treated at home. Your doctor is likely to recommend:

Antibiotics, to treat infection.

A liquid diet for a few days while your bowel heals. Once your symptoms improve, you can gradually add solid food to your diet.

An over-the-counter pain reliever, such as acetaminophen (Tylenol, others).

This treatment is successful in 70 to 100 percent of people with uncomplicated diverticulitis.

Complicated diverticulitis

If you have a severe attack or have other health problems, you'll likely need to be hospitalized. Treatment generally involves:

Intravenous antibiotics

Insertion of a tube to drain an abscess, if one has formed

Surgery

You'll likely need surgery to treat diverticulitis if:

You have a complication, such as perforation, abscess, fistula or bowel obstruction

You have had multiple episodes of uncomplicated diverticulitis

You are immune compromised

There are two main types of surgery:

Primary bowel resection. The surgeon removes diseased segments of your intestine and then reconnects the healthy segments (anastomosis). This allows you to have normal bowel movements. Depending on the amount of inflammation, you may have open surgery or a minimally invasive (laparoscopic) procedure.

Bowel resection with colostomy. If you have so much inflammation that it's not possible to rejoin your colon and rectum, the surgeon will perform a colostomy. An opening (stoma) in your abdominal wall is connected to the healthy part of your colon. Waste passes through the opening into a bag. Once the inflammation has eased, the colostomy may be reversed and the bowel reconnected.

Follow-up care

Your doctor may recommend colonoscopy six weeks after you recover from diverticulitis, especially if you haven't had the test in the previous year. There doesn't appear to be a direct link between diverticular disease and colon or rectal cancer. But colonoscopy — which isn't possible during a diverticulitis attack — can exclude colon cancer as a cause of your symptoms.

Sometimes, surgery is recommended. But previous recommendations for surgery based on the number of attacks have been questioned, since most people do well even after two or more attacks. The decision on surgery is an individual one, and is often based on the frequency of attacks and whether complications have occurred.

Eat more fiber. High-fiber foods, such as fresh fruits and vegetables and whole grains, soften waste material and help it pass more quickly through your colon. This reduces pressure inside your digestive tract. However, it isn't clear whether a high-fiber diet decreases the risk of diverticulitis. Eating seeds and nuts isn't associated with developing diverticulitis.

Drink plenty of fluids. Fiber works by absorbing water and increasing the soft, bulky waste in your colon. But if you don't drink enough liquid to replace what's absorbed, fiber can be constipating.

Some experts suspect that people who develop diverticulitis may not have enough good bacteria in their colons. Probiotics — foods or supplements that contain beneficial bacteria — are sometimes suggested as a way to prevent diverticulitis. But that advice hasn't been scientifically validated.

Experience. Each year, Mayo Clinic specialists diagnose and treat more than 2,000 people with diverticulitis.

Expert diagnosis. Symptoms of diverticulitis are similar to those of other digestive disorders. Mayo specialists have experience distinguishing diverticulitis from other conditions.

New ideas. Mayo Clinic researchers are studying ways to improve diagnosis and treatment of diverticulitis. You have access to the expertise of Mayo's clinician-researchers.

Mayo Clinic in Rochester, Minn., ranks No. 1 for digestive disorders in the U.S. News & World Report Best Hospitals rankings. Mayo Clinic in Scottsdale, Ariz., and Mayo Clinic in Jacksonville, Fla., are ranked among the Best Hospitals for digestive disorders by U.S. News & World Report. Mayo Clinic also ranks among the Best Children's Hospitals for digestive disorders.

Diverticulitis can be difficult to diagnose because abdominal pain is a symptom of many digestive disorders. Mayo Clinic has radiologists who specialize in digestive disorders and have experience distinguishing diverticulitis from other conditions.

Mayo's digestive disease specialists (gastroenterologists) have experience diagnosing the severity of diverticulitis. Precise diagnosis is important for appropriate treatment.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Mayo Clinic researchers are working to improve diagnosis and treatment of diverticulitis. Specific efforts include categorizing uncomplicated diverticulitis to better assess the likelihood of recurrence.

See a list of publications by Mayo Clinic doctors on diverticulitis on PubMed, a service of the National Library of Medicine.

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